Grace, a three-time winner on the European Tour this season, teed off on the ninth hole at The Olympic Club's Lake Course, and birdied 10 and 11 before a bogey at 12 dropped him back to one-under.

Playing partner Na had just moved atop the leaderboard at three-under through nine holes with his fourth birdie of the day at 17 when Grace rolled in his eagle putt.

They were one shot in front of American Jason Bohn, whose two birdies included one on Olympic's 520-yard first hole, all the more imposing playing as a par-four instead of the par-five it was in the four prior US Opens held here.

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